First Urban Case of Rickettsia parkeri (Atlantic Rainforest Strain) Rickettsiosis in Mérida, Mexico.

CASE DESCRIPTION: The first human case in urban ambient of infection by Rickettsia parkeri Atlantic Rainforest strain in an 8-year-old male patient is presented.

CLINICAL FINDINGS: The patient reporting a tick bite presented with fever (38 °C), myalgia, abdominal pain, arthralgia, and mild lymphadenopathy in the right axilla. A lesion was observed at the tick-bite site.

TREATMENT AND

RESULTS

A biopsy sample was obtained from the tick bite area for diagnosis by PCR and sequencing of the DNA fragment, resulting in 100% homology towards Rickettsia parkeri Atlantic Rainforest strain reported in human cases in Brazil. Treatment consisted of 100 mg of doxycycline for 10 days, with symptoms ceasing 24 hours after the start of treatment.

CLINICAL RELEVANCE: We report the first case of rickettsiosis by Rickettsia parkeri in an urban area in Mexico. Infection is considered mild to moderate, but it is unusual in urban environments. Medics should be concerned about the clinical manifestations associated with tick bites, particularly when lymphadenopathy is present.